JP2007003811A - Image display medium and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display medium and an image display apparatus adaptable for such use aspects requiring high lightness, high luminance, high gloss or the like. <P>SOLUTION: The image display medium 1A comprises a transparent substrate 2 and a color substrate 3 disposed opposing to each other at a prescribed distance, a partitioning member 5 made of a resin or the like forming a plurality of cells 4 by partitioning the gap between the substrates 2, 3, a gas stored in each cell 4, and a plurality of white particles 6A and black particles 6B having different charging characteristics, wherein the color substrate 3 has color layers 33R, 33G, 33B containing a material for enhancing reflected light quantity such as a light emitting material, light accumulating material, pearl pigment, metallic pigment, prism, regressively reflective beads, and nano pigment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display medium and an image display apparatus that perform display by moving charged particles.

  As a conventional image display medium that performs display by moving charged particles, for example, a toner display (for example, see Patent Document 1) and an electrophoretic display device (for example, see Patent Document 2) are known.

  A conventional toner display includes a transparent substrate and a color substrate that are arranged to face each other with a predetermined gap, and a plurality of white particles and a plurality of black particles that are housed together with gas between the two substrates and have different charging characteristics. By applying a direct current electric field between adjacent electrodes on each of the substrates and an alternating electric field between the two substrates, the particles are moved in a direction parallel to the substrate to display the color of the color substrate.

A conventional electrophoretic display device includes a display-side substrate and a rear-side substrate arranged to face each other with a predetermined gap, an insulating liquid and a plurality of black charged particles accommodated between the two substrates, and A color layer having a fluorescent material is provided on the side substrate, and a mode in which the color of the color layer is displayed by moving black charged particles in a direction parallel to the substrate is provided. The fluorescent material absorbs light outside the visible region, excites it, and emits light in the visible region, so that not only the visible region light is reflected by the colored layer, but also the visible region emitted from the fluorescent material. Light other than that can be effectively used, and the reflectance can be improved.
JP 2002-090903 A JP 2004-310074 A

  However, in the conventional toner display, the amount of light reflected from the color substrate is reduced due to diffuse reflection on the transparent substrate or attenuation of light transmittance. As a result, the brightness (brightness), brightness and glossiness of the color substrate are insufficient.

  Similarly, in the conventional electrophoretic display device, the amount of light reflected from the color substrate is reduced due to diffuse reflection on the transparent substrate or attenuation of light transmittance, and it is difficult to obtain a clear display.

  Accordingly, an object of the present invention is to provide an image display medium and an image display apparatus that can be adapted to a usage mode in which high brightness, high brightness, high gloss, and the like are required.

  In one embodiment of the present invention, in order to achieve the above-described object, a transparent substrate having translucency, a color substrate having a colored portion arranged to face the transparent substrate with a predetermined gap, and a color substrate The reflected light amount increasing material that is included in the coloring portion and increases the reflected light amount of external light incident through the transparent substrate, and is accommodated together with the gas between the transparent substrate and the color substrate, according to the applied electric field An image display medium comprising a plurality of charged particles moving in a direction perpendicular or parallel to the transparent substrate.

  According to the image forming medium, when the charged particles are moved in a direction parallel to the substrate, the colored portion of the color substrate increases the reflected light amount of external light incident through the transparent substrate by the reflected light amount increasing material. In addition, a display composed of the color of the charged particles and the color of the colored portion of the color substrate can be performed.

  The charged particles may be composed of two types of particles having different charging characteristics and colors. Two-color or three-color display using colored portions and particles of the color substrate is possible. In addition, two-color display using only particles is possible.

  One of the two types of particles may be white particles including the reflected light amount increasing material. Combined with the material for increasing the amount of reflected light contained in the colored layer, the brightness, luminance, glossiness, etc. can be further increased.

  As the reflected light amount increasing material, a luminescent material that converts light having a wavelength other than visible light out of the external light into visible light can be used. Thereby, the brightness can be increased.

  As the reflected light amount increasing material, a phosphorescent material that stores the external light and emits the stored light when the external light is not incident can be used. As a result, an image can be displayed even when no external light is incident.

  As the reflected light amount increasing material, a prism or a return bead that reflects the external light in the incident direction can be used. Thereby, high brightness and high gloss can be obtained.

  As the reflected light amount increasing material, a pearl pigment that interferes and reflects the external light can be used. Thereby, high brightness and high gloss can be obtained.

  A metallic pigment that specularly reflects the external light can be used as the reflected light amount increasing material. Thereby, high brightness and high gloss can be obtained.

  As the material for increasing the amount of reflected light, a nanopigment that is excited by the external light and emits plasmon can be used. Thereby, high brightness and high gloss can be obtained.

  The pigment is preferably spheroidized. The spheroidized pigment is preferable from the viewpoint of maintaining repeated display since the charged particles are less crushed and worn, the deterioration is reduced.

  The color substrate preferably has a projection height on the surface in contact with the charged particles of 1/5 or less of the particle size of the charged particles. As a result, it is possible to prevent the particles from being held by the protrusions, causing the display parts to come off due to the protrusions being removed, or causing the particles to wear away due to the collision and changing the charging characteristics to repeatedly deteriorate the display characteristics. .

  The color substrate is formed on a substrate member, a colored layer formed on the substrate member and including the reflected light amount increasing material, an electrode formed on the colored layer and generating the electric field, and the electrode. And a dielectric layer.

  The color substrate includes a substrate member, an electrode that generates the electric field formed on the substrate member, and a colored layer that includes the reflected light amount increasing material formed on the electrode. be able to. The colored layer can also serve as a dielectric layer. Alternatively, a dielectric layer may be formed on the colored layer in order to adjust a dielectric constant or to adjust adhesion to particles.

  As the reflected light amount increasing material formed on the electrode, a resin in which a thin phosphorus pen-like material (for example, titanium oxide coated mica or aluminum flake) is dispersed can be used. When this is applied on the electrode, the applied layer thickness can be reduced, so that the effective electric field strength between the front and back electrodes can be increased, and in addition to high brightness and high gloss, a higher display density can be obtained.

  As the reflected light amount increasing material formed on the electrode, a resin in which nano pigments are dispersed can be used. When this is applied on the electrode, the applied layer thickness can be reduced, so that the effective electric field strength between the front and back electrodes can be increased, and a high display density can be obtained.

  The colored portion of the color substrate may be a red colored portion, a green colored portion, or a blue colored portion colored in red, green, and blue, respectively. By moving the charged particles, a single color of red, green, and blue, or a color display that combines red, green, and blue can be displayed.

  The colored portion of the color substrate may be a yellow colored portion, a magenta colored portion, or a cyan colored portion colored in yellow, magenta, and cyan, respectively. By moving the charged particles, a single color of yellow, magenta, and cyan, or a combination of yellow, magenta, and cyan can be displayed. The colored portion of the color substrate may be any one color, for example, red, gold, silver, or two colors, for example, red and green. Due to the movement of the charged particles, it is possible to display any one color or a combination of any two colors.

  In one aspect of the present invention, in order to achieve the above-described object, the transparent substrate is included in a color substrate having a colored portion that is disposed to be opposed to the transparent substrate with a predetermined gap, and is included in the colored portion of the color substrate. A reflected light amount increasing material that increases the reflected light amount of external light incident through the substrate, and a gas that is accommodated together with gas between the transparent substrate and the color substrate, and is perpendicular or parallel to the transparent substrate depending on the applied electric field. There is provided an image display device comprising: a plurality of charged particles that move to the surface; and an electric field applying unit that applies the electric field according to image data between the transparent substrate and the color substrate.

  As the transparent substrate, for example, a transparent glass substrate, a transparent resin film such as PET (polyethylene terephthalate), PC (polycarbonate), acrylic, or a transparent resin sheet can be used, and a translucent or colored transparent substrate is also included. . The electric field is formed by applying a voltage between a pair of electrodes provided on the transparent substrate and the color substrate, respectively.

  The pair of electrodes may be disposed outside the transparent substrate and the color substrate, and one of the pair of electrodes may be disposed on one of the transparent substrate and the color substrate. As the pair of electrodes, a combination of a row electrode and a column electrode, a combination of a common electrode and a pixel electrode, or the like can be used. When the electrodes are arranged outside the transparent substrate, the light transmittance of the transparent substrate is improved and an image with high contrast can be displayed.

  According to the present invention, the amount of reflected light can be increased by the material for increasing the amount of reflected light contained in the colored portion of the color substrate. Therefore, it is possible to adapt to a usage mode in which high brightness, high brightness, high gloss, etc. are required. .

[First Embodiment]
FIG. 1 shows an image display apparatus according to a first embodiment of the present invention. The image display apparatus 100 includes an image display medium 1A having a memory property, a storage unit 101 that stores image data, a voltage application unit 103 that applies a voltage to the image display medium 1A, and image data that the storage unit 101 stores. And a control unit 102 that controls the voltage application unit 103 so as to apply a voltage corresponding to the voltage to the image display medium 1A.

  The image display medium 1A includes a transparent substrate 2 and a color substrate 3 that are arranged to face each other with a predetermined gap, and a partition member 5 made of a resin or the like that forms a plurality of cells 4 by partitioning both the substrates 2 and 3. And a gas such as air accommodated in each cell 4, and a plurality of white particles 6A and black particles 6B having different charging characteristics. In the figure, only one cell 4 is shown, but in actuality, a large number of cells are arranged in a two-dimensional array according to the number of pixels.

  The transparent substrate 2 includes, for example, a surface substrate member 20 made of a transparent glass substrate or the like, a plurality of transparent row electrodes 21 made of indium tin oxide (ITO) or the like formed on the surface substrate member 20, and these rows. It includes a dielectric layer 22 made of polycarbonate or the like that protects the electrode 21 and stabilizes the charging characteristics of the particles 6A and 6B, and as a whole has translucency. In the figure, only one row electrode 21 is shown, but actually, a plurality of row electrodes 21 are arranged in parallel to the paper surface with a predetermined interval according to the number of pixels. ing.

  The white particles 6 </ b> A and the black particles 6 </ b> B are charged with different polarities due to frictional charging caused by mutual friction. Here, the white particles 6A are negatively charged, and the black particles 6B are positively charged. White pigment particles such as titanium oxide, zinc oxide, and tin oxide can be used as the white particles 6A. As the black particles 6B, black pigment particles such as carbon black, manganese ferrite black, and titanium black can be used.

(Color board)
The color substrate 3 includes, for example, a back substrate member 30 made of epoxy resin and the like, and a plurality of copper foils formed on one side of the back substrate member 30 and arranged with a predetermined interval in the direction perpendicular to the paper surface. Column electrodes 31, a reflective layer 32 formed on the plurality of column electrodes 31, a red colored layer 33R, a green colored layer 33G, and a blue colored layer 33B formed on the reflective layer 32, and coloring The dielectric layer 34 is formed on the layers 33R, 33G, and 33B and made of polycarbonate or the like that stabilizes the chargeability of the particles 6A and 6B.

(Colored layer)
The colored layers 33R, 33G, and 33B are light-reflecting amounts of light-emitting materials (fluorescent materials), phosphorescent materials, pearl pigments, metallic pigments, prisms, regression beads, nano-pigments, and the like in a resin binder. A material in which the increasing material is dispersed can be used. Thereby, the brightness, brightness | luminance, and glossiness of each color of the colored layers 33R, 33G, and 33B can be increased. The colored layers 33R, 33G, and 33B can be formed by coating, pasting a colored sheet, screen printing, or the like.

  Since the light-emitting material (fluorescent material) converts incident light having a wavelength other than visible light into visible light, a visible light component increases and brightness can be increased. Since the phosphorescent material stores external light and releases the stored light when no external light is incident, an image can be displayed even when the external light is not incident. Pearl pigments reflect incident light by interference, metallic pigments reflect incident light by specular reflection, and prisms and return beads reflect incident light in the incident direction, resulting in high brightness and high gloss. Can be made. Since the nanopigment is excited by incident light and emits its energy (plasmon emission), the color developability can be increased.

(Flatness of color substrate)
The surface of the color substrate 3 that is in contact with the particles 6A and 6B is preferably flat from the viewpoint of repeated display maintenance. That is, if there are protrusions on the surface of the color substrate 3 that are in contact with the particles 6A and 6B, the white particles 6A or the black particles 6B are held on the protrusions, or the particles 6A and 6B collide and become difficult to move. A part of the surface of the substrate 3 is detached and becomes a nucleus of an aggregate, causing a dot defect on the display image, or the surface of the particles 6A and 6B is worn away by the collision and the charging characteristics are changed to repeatedly display characteristics. May deteriorate. For this reason, the projection height on the surface of the color substrate 3 is preferably 1/5 or less, more preferably 1/10 or less of the particle diameter of the particles 6A and 6B. Specifically, when using particles 6A and 6B having a particle diameter of 10 μm, the protrusion height is 2 μm or less, preferably 1 μm or less. When using particles 6A and 6B having a particle diameter of 5 μm, the protrusion height is 1 μm or less, preferably 0.5 μm or less.

  If the reflected light amount increasing material mixed in the colored layers 33R, 33G, and 33B protrudes high, it appears on the surface of the color substrate 3 in contact with the particles 6A and 6B, so the colored layers 33R, 33G, and 33B It is important that the reflected light amount increasing material to be mixed does not protrude high.

  In order to make the protrusion form desirable so that the above problem does not occur, the reflected light amount increasing material is mixed with the binder resin constituting the colored layers 33R, 33G, and 33B and applied onto the substrate by a known method. Alternatively, the surface of the colored layers 33R, 33G, and 33B may be planarized by pressurizing the coating film with a plate or roller immediately after coating or overcoating with a clear resin solution.

  For example, when a pearl pigment dispersed resin liquid in which a flake-shaped pearl pigment having a major axis of 1 to 30 μm and a thickness of 0.05 to 0.7 μm is mixed with a resin constituting a colored layer is applied onto a substrate, The surface of the coating film may be flattened by applying the coating film with a plate or a roller immediately after the coating process or immediately after coating. Further, after applying the pearl pigment dispersion resin liquid, it may be flattened by overcoating with a clear resin liquid.

(Color board thickness)
The reflective layer 32, the colored layers 33R, 33G, 33B, and the dielectric layer 34 positioned on the back-side column electrode 31 are preferably 1/10 or less of the distance between the front-side and back-side electrodes 21 and 31, preferably 1/25 or less. Is more preferable. Specifically, when the distance between the electrodes 21 and 31 is 50 μm, the thickness of the reflective layer 32, the colored layers 33R, 33G, and 33B, and the dielectric layer 34 is preferably 5 μm or less, and more preferably 2 μm or less. Thereby, the effective electric field strength which acts on white particle 6A and black particle 6B is securable. In particular, as the distance between the front and back electrodes 21 and 31 is narrowed, the selection of a small reflected light amount increasing material and the surface flattening process are required to satisfy the above-described protrusion form.

(Definition and measurement method)
The lightness is defined as L (lightness) in the color difference display method JIS Z 8730 and the definition and measurement method (Lab chromaticity coordinate display). Further, the definition and measurement method (diffuse illumination method) of whiteness as an index representing the brightness and whiteness of paper is defined in JIS P 8148. The definition and measurement method (75-degree specular gloss test method) of the glossiness is defined in JIS P 8142. The definition and measurement method of fluorescence are defined in JIS Z 8717. The definition and measurement method of luminance are defined in JIS Z 8724.

(Operation of the first embodiment)
Next, the operation of the image display apparatus 100 according to the first embodiment will be described. The control unit 102 controls the voltage application unit 103 so as to apply a voltage corresponding to the image data stored in the storage unit 101 to the image display medium 1A.

(1) Black and white display mode When performing black and white display using white particles 6A and black particles 6B, the voltage application unit 103 sequentially applies a selection voltage (for example, 0 V) to the row electrodes 21 under the control of the control unit 102, A positive or negative image voltage (for example, +140 V or −140 V) is applied to each column electrode 31 according to the image data for a predetermined time (for example, 30 ms).

  In a region (pixel) between the substrates 2 and 3 to which positive is applied to the column electrode 31, the negatively charged white particles 6A move to the column electrode 31 side to which positive is applied and adhere to the inner surface of the color substrate 3. The positively charged black particles 6 </ b> B move to the opposite row electrode 21 side and adhere to the inner surface of the transparent substrate 2. On the other hand, in the region where the negative is applied to the column electrode 31, the positively charged black particles 6B move to the column electrode 31 side where the negative is applied and adhere to the inner surface of the color substrate 3, and are negatively charged white particles. 6B moves to the opposite row electrode 21 side and adheres to the inner surface of the transparent substrate 2. In this way, a black and white image is displayed through the transparent substrate 2.

  Even if the application of the voltage between the electrodes 21 and 31 is stopped, the electrostatic adhesion force between the particles 6A and 6B and the dielectric layers 22 and 34 is maintained. The black and white image is displayed for a long time.

  In the initial state, an alternating voltage (for example, ± 70 V) having a predetermined frequency (for example, 800 Hz) is applied from the voltage application unit 103 to the row electrode 21, and an alternating voltage (for example, for ±±) 70V) is applied to each column electrode 31, and as a final pulse, for example, a positive DC voltage is applied to the row electrode 21, the white particles 6A adhere to the entire inner surface of the transparent substrate 2 and the black particles 6B become the color substrate 3. It adheres to the entire inner surface and returns to its initial state. At this time, when the image display medium 1A is viewed from the transparent substrate 2 side, only a white screen by the white particles 6A is visible. Further, when a negative DC voltage is applied to the row electrode 21 as the final pulse, the black particles 6B adhere to the entire inner surface of the transparent substrate 2, and the white particles 6A adhere to the entire inner surface of the color substrate 3. When 1A is viewed from the transparent substrate 2 side, only a black screen with black particles 6B is visible.

(2) Color display mode When performing color display on the color substrate 3, the voltage application unit 103 controls the row electrode 21 with an alternating voltage (for example, ± 70 V) at a predetermined frequency (for example, 800 Hz) under the control of the control unit 102. ) And an alternating voltage (for example, ± 70 V) having an opposite phase to that is applied to each column electrode 31.

  In the case of FIG. 1, in the mode for returning to the initial state, a negative DC voltage is applied to the row electrode 21 as the final pulse, and the black particles 6B are adhered to the entire inner surface of the transparent substrate 2 to display a black screen. Next, the alternating voltage is applied between the column electrode 31 and the row electrode 21 corresponding to the red colored layer 33R and the green colored layer 33G. As a result, the white particles 6A and the black particles 6B present in the pixels corresponding to the red colored layer 33R and the green colored layer 33G move to the pixels corresponding to the blue colored layer 33B to which no alternating voltage is applied.

  As a result, the red color of the colored layer 33R, the green color of the colored layer 33G, and the black color of the black particles 6B can be seen through the transparent substrate 2. As described above, even if the application of the voltage between the electrodes 21 and 31 is stopped, the immediately preceding image is maintained for a long time.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(A) Since the colored layers 33R, 33G, and 33B of the color substrate 3 can increase the amount of reflected external light incident through the transparent substrate 2 by using a material that increases the amount of reflected light, high brightness, high brightness, high gloss, etc. It becomes possible to adapt to the usage mode as required.
(B) Since the surfaces of the color substrate 3 that are in contact with the particles 6A and 6B are flat, it is possible to prevent the occurrence of dot defects on the display image and the repeated deterioration of display characteristics.

[Second Embodiment]
FIG. 2 shows an image display apparatus according to the second embodiment of the present invention. This second embodiment is different from the first embodiment in that the positions of the column electrode 31 and the reflective layer 32 are turned upside down, and the rest is configured in the same manner as the first embodiment. ing.

(Color substrate manufacturing method)
The color substrate 3 can be manufactured by several methods. For example, the reflective layer 32 is printed on the back substrate member 30, the colored layers 33R, 33G, and 33B are printed thereon, a protective layer is formed as necessary, and the electrode pattern is formed thereon by masking. An ITO film column electrode 31 is deposited, and a dielectric layer 34 is applied thereon.

  The protrusions on the surface of the colored layers 33R, 33G, and 33B are held through the column electrode 31 and the dielectric layer 34 thereon, and become protrusions on the dielectric layer 34. Accordingly, since the problem due to the protrusion occurs as in the case of the configuration of FIG. 1, it is useful to define the protrusion state as described above.

  As another reason, it is preferable to smooth the surface of the column electrode 31 in order to ensure the uniformity of the electric field strength distribution between the front and back electrodes 21 and 31. In order to smooth the surface of the column electrode 31, it is necessary to smooth the surfaces of the colored layers 33R, 33G, and 33B, and the projections of the reflected light amount increasing material contained in the colored layers 33R, 33G, and 33B are formed as described above. It is useful to make it the same form.

(Other methods for producing color substrates)
As another manufacturing method of the color substrate 3, it is useful to develop a manufacturing method called a color filter transfer method. In this method, a column electrode 31 made of an ITO film is deposited in an electrode pattern shape by masking on a temporary adhesive layer on a glass substrate, and a colored layer 33R, 33G, 33B made of a protective layer and a color filter is formed thereon, and a reflective layer 32. The back substrate member 30 made of an adhesive layer and a plastic base material is laminated in this order. Thereafter, the temporary adhesive layer is peeled off to obtain a plastic color filter having a smooth ITO film on the top. This can be developed on the back color substrate. A color filter material, a high luster material, a high gloss material, etc. are mixed in a part of the color filter to produce a plastic color filter by a transfer method, and a desired dielectric layer 34 is formed on the column electrode 31. Thus, the color substrate 3 is obtained.

  In this configuration, a colored layer containing a color-forming material, a high-gloss material, a high-gloss material, etc. is formed on a smooth ITO film via a protective layer, so that the color-forming material, high-gloss material, high-gloss material, etc. The protruding state of the colored layer derived from the above affects the adhesion with the adhesive layer with the plastic substrate, but does not affect the surface of the dielectric layer 34 in contact with the particles 6A and 6B. Is not a problem for the movement of particles. Except for the large number of steps of transfer, this is a useful method for producing the color substrate 3.

(Effect of the second embodiment)
According to the second embodiment, the following effects can be obtained.
(A) Since the colored layers 33R, 33G, and 33B of the color substrate 3 can increase the amount of reflected external light incident through the transparent substrate 2 by the reflected light amount increasing material, as in the first embodiment. The present invention can be applied to usages that require high brightness, high brightness, high gloss, and the like.
(B) Since the electrodes are arranged on the colored layers 33R, 33G, and 33B, the surface that contacts the particles 6A and 6B of the color substrate 3 can be easily flattened as compared with the first embodiment.

  In addition, this invention is not limited to said each embodiment, A various deformation | transformation is possible. In addition, the constituent elements of each embodiment can be arbitrarily combined without departing from the scope of the present invention.

  In each of the above embodiments, the combination of R, G, and B has been described as the colored layer. However, a combination of YMC may be used, and a single color or a combination of other colors may be used depending on the purpose.

  Moreover, in each said embodiment, although gas was accommodated in each cell 4, when the attenuation | damping with a liquid does not become a problem because the distance between a transparent substrate and a color substrate is short, for example, it is colorless to each cell 4. A liquid may be contained.

1 is a diagram illustrating a schematic configuration of an image display device according to a first embodiment of the present invention. It is a figure which shows the schematic structure of the image display apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1A, 1B Image display medium 2 Transparent substrate 3 Color substrate 4 Cell 5 Partition member 6A White particle 6B Black particle 20 Surface substrate member 21 Row electrode 22 Dielectric layer 30 Back substrate member 31 Column electrode 32 Reflective layer 33R, 33G, 33B Colored layer 34 Dielectric layer 100 Image display device 101 Storage unit 102 Control unit 103 Voltage application unit

Claims (18)

A transparent substrate having translucency;
A color substrate having a colored portion disposed opposite to the transparent substrate with a predetermined gap;
A reflected light amount increasing material that is included in the colored portion of the color substrate and increases the reflected light amount of external light incident through the transparent substrate;
An image display comprising: a plurality of charged particles that are accommodated together with a gas between the transparent substrate and the color substrate and move in a direction perpendicular or parallel to the transparent substrate in accordance with an applied electric field. Medium.   The image display medium according to claim 1, wherein the charged particles include two types of particles having different charging characteristics and colors.   The image display medium according to claim 2, wherein one of the two types of particles is a white particle including the reflected light amount increasing material.   The image display medium according to claim 1, wherein the reflected light amount increasing material is a luminescent material that converts light having a wavelength other than visible light out of the external light into visible light.   The image display medium according to claim 1, wherein the reflected light amount increasing material is a luminous material that stores the external light and emits the stored light when the external light is not incident. .   The image display medium according to claim 1, wherein the reflected light amount increasing material is a prism or a regression bead that reflects the external light in an incident direction thereof.   4. The image display medium according to claim 1, wherein the reflected light amount increasing material is a pearl pigment that interference-reflects the external light. 5.   The image display medium according to claim 1, wherein the reflected light amount increasing material is a metallic pigment that specularly reflects the external light.   The image display medium according to claim 1, wherein the reflected light amount increasing material is a nanopigment that is excited by the external light and emits plasmon.   The image display medium according to claim 7, wherein the pigment has been spheroidized.   2. The image display medium according to claim 1, wherein a protrusion height of a surface of the color substrate in contact with the charged particles is 1/5 or less of a particle diameter of the charged particles.   The color substrate is formed on a substrate member, a colored layer formed on the substrate member and including the reflected light amount increasing material, an electrode formed on the colored layer and generating the electric field, and the electrode. The image display medium according to claim 1, further comprising a dielectric layer.   The color substrate includes a substrate member, an electrode for generating the electric field formed on the substrate member, and a colored layer including the reflected light amount increasing material formed on the electrode. The image display medium according to claim 1.   The image display medium according to claim 13, wherein the reflected light amount increasing material formed on the electrode is made of a resin in which a thin phosphorus pen-like material is dispersed.   The image display medium according to claim 13, wherein the reflected light amount increasing material formed on the electrode is made of a resin in which a nano pigment is dispersed.   The image display medium according to claim 1, wherein the colored portions of the color substrate are a red colored portion, a green colored portion, and a blue colored portion that are colored red, green, and blue, respectively.   The image display medium according to claim 1, wherein the colored portion of the color substrate is a yellow colored portion, a magenta colored portion, and a cyan colored portion that are colored yellow, magenta, and cyan, respectively. A transparent substrate having translucency;
A color substrate having a colored portion disposed opposite to the transparent substrate with a predetermined gap;
A reflected light amount increasing material that is included in the colored portion of the color substrate and increases the reflected light amount of external light incident through the transparent substrate;
A plurality of charged particles that are accommodated together with a gas between the transparent substrate and the color substrate and move in a direction perpendicular or parallel to the transparent substrate in accordance with an applied electric field;
An image display apparatus comprising: an electric field applying unit that applies the electric field according to image data between the transparent substrate and the color substrate.